Legal Question in Family Law in California

It could depend on what the custody order says. If bio-dad doesn't have any custodial rights, then he would have to establish them before collecting the children. If he has legally confirmed paternity and any custodial rights without applicable limitations (e.g., supervised visitation), and the mother is jailed, he shouldn't have much trouble getting the kids. He might want a police escort on "civil standby."

If he doesn't have confirmed paternity or custodial rights, he will need to file something in NV to get that started, and then apply to the court for emergency temporary custody.